Organic Analysis at the Hanford Nuclear Site - Analytical Chemistry

Organic Analysis at the Hanford Nuclear Site. J. A. Campbell ,. R. W. Stromatt ,. M. R. Smith ,. R. M. Bean ,. T. E. Jones ,. D. M. Strachan. Anal. Ch...
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Organic Analysis at the

Special techniques are needed to cope with the high radioactivity, ionic strength, and extreme pH of mixed nuclear wastes

T

he 560-square-mile Hanford reservation, located ~ 120 miles south of Spokane, WA, and 220 miles southeast of Seattle, was built by the U.S. Army Corps of Engineers and DuPont in 1943 to produce plutonium for nu-

J. A. Campbell, R. W. Stromatt, M. R. Smith, D. W. Koppenaal, R. M. Bean, T. E. Jones, and D. M. Strachan Pacific Northwest Laboratory

H. Babad Westinghouse Hanford Company 1208 A

clear weapons during World War II. Plutonium production continued until January 1987, when the last production reactor ceased operation. As a result, large quantities of mixed radioactive wastes were generated. Major chemical processing facilities were constructed to reprocess fuel from nine production reactors and to recover enriched uranium, radioactive cesium, and strontium. However, reprocessing and other waste management operations created even more inorganic and organic radioactive mixed waste, much of which is stored in underground tanks.

Analytical Chemistry, Vol. 66, No. 24, December 15, 1994

The U.S. Department of Energy (DOE) operates the Hanford site, which it inherited from the Manhattan Engineering District of the U.S. Army Corps of Engineers, the Atomic Energy Commission, and the Energy Research and Development Administration. Of all the nuclear weapons production facilities in the United States, the Hanford site currently accounts for the largest volume percentage of defense-related high-level waste (HLW). After ~ 40 years of nuclear weapons production, Hanford must now deal with the legacy of nearly 1100 waste sites, in0003-2700/94/0366-1208A/$04.50/0 © 1994 American Chemical Society

Hanford Nuclear Site eluding liquid-release areas (e.g., trenches and cribs), burial grounds, and liquid and solidified wastes in tanks. Sixty-eight single-shell tanks (SSTs) have or are suspected to have leaked. In addition, from 1946 to 1966, large volumes of liquid wastes were intentionally discharged to the soil. At the time, the methods used by Hanford operators for treatment, storage, and disposal of the various waste streams were commonly accepted, but those practices would not meet today's stringent regulatory standards. In this Report, we present a brief history of the chemical processes at the Hanford site; describe the storage of wastes in underground tanks; and review problems associated with sampling, sample preparation, and analysis of organic constituents in tank waste. Waste processing To understand the genesis of nuclear waste management problems at Hanford, it is necessary to examine the chemical separations processes that produced the waste materials. The relationships among disposal technology, waste types, reprocessing methods, and storage facilities are all intertwined. In the overall disposal strategy, wastes high in fission products went to tanks and low-level wastes (LLWs) were discharged to the soil. To help alleviate the shortage of tank space, certain waste streams were treated to further reduce the radionuclide concentrations before discharging them to the soil. To reduce waste volumes, evaporator systems were added to the waste-processing methods in the late

1970s and early 1980s. To reduce the "heat" load in the tanks, certain wastes were processed further to remove 137Cs and 90Sr. The chemical complexity and volume of the wastes increased with each reprocessing step; movement of wastes among the 149 SSTs and 28 double-shell tanks (DSTs) led to a commingling of waste types. Three Pu recovery processes were used at Hanford. The BiP0 4 batch process (1) was based on selective coprecipitation of Pu (IV) with BiP0 4 after dissolution of irradiated fuel; it did not recover U directly. The "Redox" recovery process was a more efficient continuous solvent extraction process in which A1(N03)3 was used as a salting-out agent and aqueous reducing agents were used for selective control of Pu and U oxidation states and solubilities (2). It provided direct recovery of both U and the organic solvent but released high salt concentrations into the aqueous waste stream, which hindered the evaporation process for volume reduction. The third, or "Purex" method, used tributyl phosphate (TBP) as the extractant, kerosene as the solvent (3), and nitric acid for salting out; it required fewer extraction steps than the Redox process and recovered Pu and U along with most of the nitric acid. Normal paraffinic hydrocarbon (NPH; C12-C14) later replaced the kerosene. Disposal Highly radioactive waste has been stored "temporarily" in large underground storage tanks at the Hanford site since 1944. More than 227,000 m3 (60 million gal) of

waste have accumulated in 177 tanks. Chemical processing of irradiated nuclear fuels produced alkaline liquors and solids containing a wide variety of radionuclides and hazardous chemicals in the form of unsegregated liquids, slurries, salt cakes, and sludges. Storage tanks. Figure 1 shows a typical Hanford SST. The 23-m (75-ft) diameter domed-top tanks consist of shells of reinforced concrete lined with carbon steel along the bottom and sides. The tank capacities vary from 2000 to 3800 m3 (530,000-1 million gal). The 2000 m3 and 3000 m3 tanks were originally arranged in cascades of three, four, or six tanks, allowing fluids to overflow from tank to tank and leave the solid residues behind. When the first tank in a series was filled, it overflowed to the second tank, then to the third tank, and so on. Most tanks have a minimum soil cover of 2 m (6 ft) over the dome. Access to all the tanks, important for sampling, is provided by risers penetrating the domes. Risers vary in diameter from 0.1 to 1 m. The number of risers allowing access is limited, and the number that are accessible for sampling varies from tank to tank. Waste types stored in SSTs have been described by Anderson (4) and Lucas (5). The "tracks radioactive components" (TRAC) study was one attempt to estimate the total waste inventory and to characterize the waste in each SST (6). Several of the 49 waste types discharged to SSTs were complex concentrate (CC) containing organic metal ion chelators, organic wash waste from the Purex plant, decontamination waste (DW), and neutralized

Analytical Chemistry, Vol. 66, No. 24, December 15, 1994 1209 A

Report aqueous TBP waste. Many SSTs also contain incidental wastes, such as failed equipment and materials discarded from development and testing activities that took place when the plants were still operating. Between 1943 and 1964,149 SSTs were built at the Hanford site. No wastes have been added to the tanks since November 1980. For a little more than a decade, waste has been stored in the 28 DSTs built between 1968 and 1986. These have a tank-in-tank design with a capacity of 3800 m 3 (1 million gal). The pumpable liquors have been removed from most of the SSTs and transferred to the more environmentally sound DSTs to prevent further leakage into the surrounding soil. Discharge to the soil. Wastes were discharged to the ground during the 1940s and 1950s as part of the early Pu and U recovery operations. Documents show that approximately 456,000 m3 (120 million gal) of liquid waste were intentionally discharged from SSTs (7). Wastes were discharged to cribs (similar to septic tank drainage fields), retention trenches (8), ponds, and other structures that allowed liquid to seep into the ground. Safety issues Safety studies and evaluations have been conducted periodically as new wasteproducing processes have been developed and as the resulting waste conditions have changed. However, uncertainties about permanent waste disposal, the continual pressure of waste generation on limited storage space, and aging facilities have resulted in several safety concerns (9,10), including flammable gas generation, potentially explosive mixtures of ferrocyanide, and potential organicnitrate reactions in the tanks. The DOE removed the SSTs from service in 1980 and started a program to temporarily stabilize the tanks by removing pumpable liquid. The DOE, the U.S. Environmental Protection Agency (EPA), and the Washington State Department of Ecology have agreed that all SSTs must be characterized by 1998 and closed by 2018 (11). As part of the characterization requirements, a minimum of two core samples will be taken from each SST for determination of chemical, radiological, and physical properties. 1210 A

Analytical

Chemistry,

Hot cell

fec'/''t'

Sampling The need to protect workers, facilities, and equipment from undue exposure and to maintain good analytical protocol also affects the choice of sampling technique. In some instances, EPA SW-846 (suggested guidelines and methods for sampling and analysis of solid wastes) methodology is followed (12). This sampling methodology is workable for storage drums, filter cakes, and other easily accessible matrices. To sample underground mixed-waste storage tanks, special devices and techniques have been devised. The matrices found within the storage tanks are rarely uniform from top to bottom, from tank to tank, or even from one side of a tank to the other. Different sampling techniques may be required for different waste tanks. For example, in tanks that have a floating organic layer, a "bottle-on-a-string" sampler is used to sample organic and aqueous layers (13,14). By sampling and by remote television inspection, Griest (15) has determined that tanks at Oak Ridge National Laboratory (ORNL) generally contain a liquid phase layered over sludge phases of various consistencies. At ORNL the liquid layers were sampled by suction and collected in a trap jar. A second "safety surge jar" and high-efficiency particulate air (HEPA) filters on the vacuum pump were used to minimize release of radiation. Because of the high radiation involved, collecting the 1-L volume specified in EPA SW-846, Method 3510, was judged too hazardous and the sample size was reduced 50-fold. The sludge layers were

Vol. 66, No. 24, December

15, 1994

sampled by coring. The soft-sludge sampler had a spring-loaded bottom closure, and the hard-sludge sampler had a cutting edge for better penetration and a gate valve to retain the sample. Tank waste at the Hanford site is characterized mainly by laboratory analysis of core samples taken from the surface via rotary core sampling through one of the tank risers. The 1-in. diameter cores are usually obtained in ~ 20-in. segments that are transported to the lab in a radiationshielded container and extruded from the container in a heavily shielded laboratory "hot cell." A hot cell is a room built with very thick walls (~ 1.3 m) and equipped with a sample entry port, viewing windows made of leaded glass and filled with oil, and remote manipulators. All sample preparation is done in the hot cell through the use of remote-controlled mechanical arms and laboratory equipment (see photo). Sample preparation The hot cell facilities are used for sample dissolution, dilution, solvent extraction and, occasionally, analysis. A hot cell must be used for highly radioactive wastes (~ 3-11 R/h). Sample turnaround is much lower in the hot cell facilities, and special training is required to use diem. Wastes with low-to-moderate specific or total radioactivity (~ 1 R/h) may be prepared and analyzed outside the hot cell in a radiation hood or a glovebox. The actual cutoff levels that differentiate lab bench work, glovebox work, and hot cell work are usually based on local practice or the judgment of the resident health physicist. Nuclear wastes may exhibit complex physicochemical properties. Such wastes are often multiphasic (i.e., aqueous and organic liquid phases and solid phases), have high ionic strength (e.g., 8.3 mol/L Na, 0.2 mol/L Al, 4.4 mol/L nitrate and nitrite, 0.01-2 mol/L hydroxide), are very acidic or alkaline, and are extremely radioactive (often 1 Ci/L, primarily because of the presence of alpha and gamma emitters). They can also contain up to 3.7 mol/L total organic carbon (TOC). These properties may result in unexpected sample behavior during preparation and chemical analysis. For example, acidification may result in excessive foaming and extensive formation of solids.

Analysis

Waste characterization includes analyses for organics, inorganics, radionuclides, and the determination of physical properties. The following discussion is limited to organic compound characterization. This is not to say that challenges are not associated with other characterization efforts; problems associated with high radiation, difficult matrices, sample integrity, and sample homogeneity apply to the entire characterization process. However, characterization of organics has perhaps been more of a challenge because of the relative lack of experience in performing organic analyses of such complex samples at the DOE sites. Because of environmental, health, and safety concerns, the organic analysis group formed at Hanford in 1988 decided to implement EPA protocols of the Contract Laboratory Program (CLP) Statement of Work (SOW) 2/88 (16). The CLP analyses are performed routinely for semivolatile organic compounds (SVOCs) and VOCs by GC/MS. Other analyses performed on a routine basis include TOC and extractable organic halide (EOX).

Dome elevation benchmark attached to dome riser

Semivolatile organics. The first samples received for characterization were from tank wastes—most from SSTs and a few from DSTs. The amount of sample available for organic and other analyses was limited because of the large number of analyses needed to satisfy characterization requirements. Consequently, the adapted method was originally used for medium-level contaminated soils. Very little radioactivity from the samples is extracted into the organic phase, so the extracts can be transferred to openface radiochemistry hoods for further processing. Most radioactivity remaining after concentration of the extract is removed by filtration or centrifugation. Extracts from samples containing complexation agents and high concentrations of methanol usually retain additional radioactivity, but even those can be processed in the radiochemistry hoods. Aqueous samples (drainable liquids) from core segments are analyzed separately. Nominal 1-g samples are diluted with water and extracted into methylene chloride from samples at pH > 11 and then at pH < 2. Samples containing excessive

Tank breather filter with pressure-relief system

amounts of NPH are cleaned up by treating the base-neutral fraction extract with a silica gel solid-phase extractor developed at Pacific Northwest Laboratory. Radioactive soil samples from around crib waste areas have also been analyzed for SVOCs. These samples are prepared according to the low-level soil/sediment procedure and, because of relatively low radioactivity, most are prepared for analysis in radiochemistry hoods. GC/MS analysis of the extracts also follows the 2/88 SOW. Almost none of the tank waste samples contain detectable concentrations of EPA target compounds, and the number of unidentified library search compounds varies considerably. Library search compounds found most often in the tank waste are a variety of oxidized compounds, «-alkanes (primarily NPH), and TBP. Also detected are longer chain branched alkanes and some alkenes. Most soil samples present a similar picture. Chromatograms of some samples contain broad regions of unresolved peaks whose spectra indicate the presence of complex alkane mixtures, acids, alcohols, or mixtures of all of these.

Exhauster (for selected tanks)

Leak detection lateral caisson and instrument enclosure (241 A a n d SX tank f a r m s oniy) " "

1

Leak detection drywells

Temperature profile thermocouple tree

Leak detection laterals (241-A and -SX tank farms only)

Figure 1 . Typical design for a single-shell tank. Analytical Chemistry, Vol. 66, No. 24, December 15, 1994 1211 A

Report One early problem with SVOC determinations resulted from the core sampling process used to obtain waste tank samples. To prevent tank waste from rising in the sampler while removing a core segment, NPH was used as a hydrostatic fluid. Consequently, the sample extracts required such large dilutions that the only result of the analysis was confirmation that NPH was used in the sampling process (17). In addition, silicone lubricant from the sampler dissolved in the NPH and was carried through the sample preparation process, resulting in instrument and chromatographic problems. NPH dominated the total ion chromatogram (TIC) and persisted even after numerous injections. In some instances, 10,000-fold dilutions were required to alleviate the problem. Use of the NPH sample cleanup precluded determination of NPH native to the sample but, fortunately, NPH has been replaced with water for most, and certainly for critical, sampling. Deuterated phenolic compounds are commonly used as surrogate and matrix spikes. Poor acid surrogate and matrix spike recoveries were observed in the analysis of extracts from some samples, mostly from SST sludges and drainable liquids, but also from some soil samples taken at crib waste sites. Nitration products of these phenolic spikes appeared in some of the extracts from such samples. To examine the cause, surrogate and matrix spike compounds from simulated drainable liquid were extracted as a function of pH. Below pH ~ 5, recovery of some of the acids was reduced and was accompanied by the formation of a nonstoichiometric quantity of nitrated phenolic compounds. Above pH 7-8, recoveries of the acids were sharply reduced, as would be expected from their pifas; the base-neutral spikes behaved as expected. Because of the specialized methods used in the hot cells to adjust sample pH, the control of sample pH probably affects acid spike recovery more than the sample matrix does. Some samples, particularly those from one H2-generating waste, include constituents that elevate chromatographic baselines. The TOC content in these samples is high—carbon residue appears on the glass wool in the injection port liner after analysis—and the radioactivity level in the 1212 A

extracts is greater than that measured in most other tank samples. These findings agree with process documents recording the presence of organic chelating agents in the tank. Using methylene chloride with a high concentration of methanol (e.g., for matrix spiked samples) to extract drainable liquid and sludge samples with a high water content occasionally results in the formation of a second organic phase. GC/MS of such a phase from the extraction of a simulated drainable liquid showed reduced abundance of some internal standards, the presence of nitrated acid spike compounds, and an elevated baseline. Mass spectra of the elevated-baseline region of the chromatogram revealed the presence of column degradation products. Furthermore, chromatograms of extracts from some matrix spiked samples contained peaks that were absent in the chromatogram of the unspiked sample. These peaks may be from more polar compounds than those usually extracted in methylene chloride; Stromatt et al. have developed a method to minimize this problem (18). Volatile organics. As with the SVOC analyses, the first samples analyzed for VOCs as part of the characterization requirements were from SSTs. Other samples routinely analyzed include the soil from around the crib waste and lab waste streams. The highly radioactive samples are treated in the hot cells according to the CLP medium-level procedure (16) and are extracted with methanol. The metha-

nol extract, which is usually about 100-fold less radioactive than the sample, is transferred to a radiochemistry hood where it is injected into a cold purge-and-trap unit interfaced to a GC/MS system. Samples collected using NPH as a hydrostatic fluid are effectively separated from NPH by using a novel closed-system C18 SPE procedure developed at Pacific Northwest Laboratory (19). The analysis for VOCs also follows the CLP methods. Very few EPA target compounds have been found in any one sample. Those identified include 1,1,1trichloroethane, toluene, acetone, 2-butanone, tetrachloroethene, chloroform, and methylene chloride, almost all below quantitation limits. The only library search compounds found were n-alkanes (C10C14) and silicone lubricant constituents or their decomposition products. Target compounds found in the soil samples from the crib waste area include 1,1,1-trichloroethane, chloromethane, toluene, and methylene chloride, almost all below quantitation limits. Library search compounds found included oxidized organics, alkenes, «-alkanes (C10-C14), and branched alkanes. VOC analysis has not been plagued with as many problems as SVOC analysis. However, aerosol formation caused corrosion of purge-and-trap lines and valves and usually resulted in deposition of material in the GC column after thermal desorption of the trap column. This problem was solved by adding an improved aerosol trap.

Table 1 . Results of derivatization GC/MS analyses on tank core segment samples Concentration of major components (mg C/g sample)

Sample No.

NIDA

NTA

CA

ED3A"

EDTA

SA

TOC"

%TOC accounted for

R4258/C R4259/C R4260/C R4261C R4262/NC R4263/NC

1.30 0.88 1.00 0.97 0.24 1.40

0.40 0.32 0.30 0.29 0.06 0.37

0.44 0.22 0.38 0.23 0.14 0.47

0.19 0.18 0.50 0.34 0.32 0.24

2.00 1.30 1.70 3.90 0.81 0.79

0.07 0.05 0.08 0.08 0.02 0.08

4.8 3.3 5.0 6.4 2.2 3.5

44 33 46 52 20 32

a

Assuming response similar to EDTA. " Total includes minor components not included in this summary table. C: convective layer; NC: nonconvective layer; NIDA: nitrosoiminodiacetic acid; NTA; nitrilotriacetic acid; CA: citric acid; ED3A: ethylenediaminetriacetic acid; EDTA: ethylenediaminetetraacetic acid; SA: succinic acid.

Analytical Chemistry, Vol. 66, No. 24, December 15, 1994

Some samples contain surfactants and foam when purged. When this occurs, the purge is stopped, the sample diluted, and the purge repeated. In highly alkaline samples, the internal standard bromochloromethane is occasionally converted to chloromethane. The NPH cleanup procedure is necessary for samples obtained using NPH as a hydrostatic fluid, but it is time consuming and does not remove all the silicone lubricants or decomposition products. The presence of radionuclides also precludes the use of an autosampler because of the radioactive contamination risks of unattended operation. Total organic carbon. TOC in tank waste and other related samples is determined by either thermal or hot persulfate decomposition of the organics followed by coulometric titration for C0 2 measurement. Highly radioactive samples are analyzed by the hot persulfate method. The reaction vessel sits in a hot cell, and the remaining instrument components are arranged outside in an adjoining radiochemistryhood. Less radioactive samples are analyzed in the hood by using thermal decomposition. Initially, thermal decomposition was also performed in the hot cell, but analyzing alkaline tank waste samples drastically shortened the lifetime of the furnace tube, which is very difficult to replace in the hot cell. The hot persulfate method relieved the concern that C0 2 formed during thermal decomposition could react with the alkaline matrix and lead to low TOC results. Less radioactive aqueous samples are usually analyzed by using UVcatalyzed persulfate to oxidize the organic component and nondispersive IR spectroscopy to measure C0 2 . The most difficult problem encountered thus far with the hot persulfate method has been the presence of an unknown constituent or reaction product from some samples in the titration cell that causes a continuous titration and the loss of VOCs in the analysis. A recent comparative study of TOC methods confirmed problems in the analysis of samples containing VOCs (20). The main problems with thermal decomposition have been the thermal instability of heavy metal carbonates and the unpredictable effect of the sample matrix on the decomposition temperature of the organic compounds.

0

2

4

6

10 12 14 16 18 20 22 24 26 28 30 32 34 36 Time (min)

Figure 2. Total ion chromatogram of derivatized tank sample.

Our experience with the CLP methods to date indicates that a broader based analysis scheme is needed to achieve a reasonable characterization of the organics in the Hanford wastes. Aside from NPH and TBP, very few library search compounds are identified. Furthermore, the carbon balance estimated from the TOC and GC/MS analyses is very poor for most samples. Evidence suggests that the sample preparation procedures do not extract the more polar semivolatile compounds, and the CLP methods do not address determination of nonvolatile organics. Other organic analytes

Standard methods for analyzing organic compounds in wastes are inadequate for Hanford's needs. The EPA methods were not designed to determine many of the organic chelators and other nonvolatile compounds found in high concentration in some Hanford wastes. Chelators. Chelating compounds such as EDTA, HEDTA, and nitrilotriacetic acid (NTA) are not part of the EPA list of targeted hazardous chemicals; nevertheless, they are generating renewed environmental interest. Hundreds of tons of EDTA and HEDTA have been used in defenserelated activities at the Hanford site (21). These chelators are now part of the complex mixed wastes. They form watersoluble compounds with most heavy met-

als, thereby enhancing the migration of heavy metals in soils (22,23). Recent studies with simulated wastes indicate that chelator degradation is vigorous (24, 25). No generally accepted methods exist for the determination of chelators, chelator fragments, or low molecular weight acids in radioactive mixed hazardous wastes. The polarity and nonvolatility of chelators preclude direct determination by GC/MS; therefore, chemical derivatization is required. In the initial stages of sample analysis, all preparation was performed in the hot cell facility. A waste sample was stirred overnight with water and filtered, and the aqueous leachate was dried and derivatized with BF3/CH3OH to form the methyl esters. After extraction, the chloroform solution containing the methyl esters was removed from the hot cell for GC/MS analysis. Only 10-20% of the TOC (as measured by persulfate oxidation) could be accounted for. To control the conditions for complete derivatization, including temperature and sample dryness, derivatization would have to be performed in a fume hood, but first the radioactivity levels would have to be reduced. We found that using a cation exchange resin (sodium form) reduces radioactivity levels by a factor of 500 without introducing or removing organic carbon. While testing various resins, we discovered that the hydrogen-binding form of the

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resin removes organic carbon. Incorpora­ tion of a cation exchange resin into the separation procedure was probably the most instrumental step in increasing the TOC accountability. Six samples from the H2-generating waste mentioned above have been ana­ lyzed using derivatization GC/MS; a total ion chromatogram is shown in Figure 2. The major components detected were EDTA, nitrosoiminodiacetic acid (NIDA), NTA, citric acid, succinic acid, and ethylenediaminetriacetic acid (ED3A). The che­ lator of highest concentration was EDTA in all six samples analyzed. The amount of organic carbon accounted for by deriva­ tization GC/MS varies from 20 to 52% of the TOC, depending on the sample. Pre­ liminary results indicate that the chelators and chelator fragments constitute more of the organic carbon in the upper or convective layer than they do in the lower or nonconvective layer. Table 1 lists the con­ centrations of the chelators and chelator fragments in successive waste layers. Acids. An LC method was developed to analyze low molecular weight acids such as oxalic, acetic, and formic acids. An an­ ion exchange chromatography method was developed to determine oxalic acid in waste samples, and an anion exclusion chromatography method was developed for the analysis of acetic, glycolic, and formic acids. Approximately 23-61% of the TOC is accounted for by these acids. Oxalic acid constitutes ~ 40% of the TOC in the nonconvective layer samples. The concentration of oxalate in the nonconvec­ tive layer is 3-4 times higher than in the convective layer. The sample from the low­ est layer contains the highest percentage of water-soluble organic carbon as low mo­ lecular weight acids. In addition, thermo­ spray LC/MS was used to identify low mo­ lecular weight acids (26,27). With these newly developed methods for chelators and low molecular weight acids, 71-93% of the TOC can be accounted for. Nitroso compounds. Nitroso com­ pounds have been identified using GC/MS after derivatization of the waste extracts with BF3. These compounds are impor­ tant because of the health risks associated with them. They have been identified by using thermospray LC/MS with an acidic mobile phase and by taking a GC/MS TIC after using dimethyl sulfate as the de1214 A

rivatizing reagent under basic conditions. A thermospray LC/MS method using a basic mobile phase indicated that the ni­ troso compounds identified in the TIC were artifacts of the derivatization proce­ dure. A reaction mechanism was pro­ posed for the formation of these com­ pounds under acidic or basic derivatiza­ tion conditions in the presence of high concentrations of nitrites (26,27). In view of the fact that derivatization is time consuming and labor intensive and produces artifacts as well as derivatives that are stable for ~ 24 h without ade­ quate drying, other techniques such as electrospray ionization MS and capillary electrophoresis, which require no deriva­ tization, are being evaluated for the direct analysis of tank waste. Preliminary results obtained with these techniques have been promising. Analytical methods for mixed hazardous wastes are being catalogued in a comprehensive manual that emphasizes methods for radioactive waste (28). The future of Hanford The agreement between DOE, EPA, and Washington State for the Hanford site calls for upgrading the disposal sites, closing the SSTs, and cleaning up nearby contami­ nated soil. The most immediate goals are to upgrade the liquid effluent discharge systems to prevent leaks to the Hanford soil and to pump liquids from leaking sin­ gle-shell HLW tanks. At Hanford there are billions of cubic meters of contaminated soil and tens of millions of gallons of HLW, much of which was disposed of with little or no documentation. Plumes of hazard­ ous chemicals and radionuclides under­ lie ~ 150 square miles of the desert land­ scape. For effective remediation, re­ searchers must start by characterizing the wastes and the behavior of their constitu­ ents in situ. The authors acknowledge Westinghouse Han­ ford Company for support of this work. Pacific Northwest Laboratory is operated for me U.S. Department of Energy by Battelle Memorial In­ stitute under Contract DE-AC06-76RLO 1830. The authors thank Wayne Cosby and Karen Wahl for many helpful suggestions. References (1) Ryan, J. Presented at the Hanford Techni­ cal Exchange Program, Process Chemis­ try at Hanford, Richland, WA, September 1993.

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(2) REDOX Technical Manual; Document No. HW-18700; Hanford Works: Richland, WA, 1951; Vols. 1-3. (3) PUREX Technical Manual; Document No. HW 31000; Hanford Atomic Products Op­ eration: Richland, WA, 1955. (4) Anderson, J. D. Report No. WHC-MR0132; Westinghouse Hanford Company: Richland, WA, 1990. (5) Lucas, G. E. Report No. WHC-SD-ER-I001; Westinghouse Hanford Company: Richland, WA, 1990. (6) Jungfleish, F. M. Report No. SD-WM-TI057; Rockwell Hanford Operations: Rich­ land, WA, 1984. (7) Waite, J. L. Report No. WHC-MR-227; Westinghouse Hanford Company: Rich­ land, WA, 1991. (8) Haney, W. Α.; Hanstead, J. F. Report No. HW-54599; Hanford Atomic Products Op­ eration: Richland, WA, 1958. (9) Wilson, G. R; Reep, I. E. Report No. WHXEP-0422; Westinghouse Hanford Com­ pany: Richland, WA, 1991. (10) Babad, H.; Defigh-Price, C; Fulton, J. C. Report No. WHC-SA-1661; Westinghouse Hanford Company: Richland, WA, 1992. (11) Hanford Federal Facility Agreement and Consent Order; U.S. Department of En­ ergy: Richland, WA, 1989; 89-10. (12) Test Methods For Evaluating Solid Waste; U.S. Environmental Protection Agency. U.S. Government Printing Office: Wash­ ington, DC, 1986; SW-846, Revision 3. (13) Sampling Procedure for Underground Stor­ age and Catch Tanks; Document No. T0089-010, Revision B-10; Westinghouse Hanford Company, Richland, WA, 1993. (14) Pool, K. H.; Bean, R M.; Campbell, J. A. Report No. PNL-9403; Pacific Northwest Laboratory: Richland, WA, 1994. (15) Griest, W. H. Presented at the DOE Na­ tional Tank Waste Characterization Work­ shop, Richland, WA, June 1991. (16) U.S. Environmental Protection Agency Contract Laboratory Program, Statement of Work for Organic Analysis, 2/88, 3/90, and 1/91. (17) Hoppe, E. W.; Stromatt, R W.; Campbell, J. A; Steele, M. J.; Jones, T. E. Report No. PNL-8098; Pacific Northwest Labora­ tory: Richland, WA 1992. (18) Stromatt, R W.; Hoppe, E. W.; Steele, M. J. Report No. PNL-8927; Pacific North­ west Laboratory: Richland, WA 1992. (19) Lucke, R B.; Campbell, J. A; Ross, G. A; Goheen, S. C; Hoppe, E. W. Anal. Chem. 1993,65,2229-35. (20) Baldwin, D. L.; Stromatt, R W.; Winters, W. I. Presented at SPECTRUM-94 Nu­ clear and Hazardous Waste Management International Topics Meeting, Atlanta, GA August 1994. (21) Metcalf, S. G. Report No. RHO-SA-218; Rockwell Hanford Operations: Richland, WA 1991, pp. 1-32. (22) Means, J. L; Crerar, D. A; Duguid, J. O. Science 1978,200,1477-82. (23) Toste, A P.; Kirby, L. J.; Pahl, T. R Pro­ ceedings of the 5th Annual Participants' In­ formational Meeting DOE Low-Level Waste Management Program; Denver, CO, Sept. 11-12,1984. (24) Toste, A. P. /. Radioanal. Nucl. Chem. 1992,161,549-59.

(25) Strachan, D. M. Report No. PNL-8278; Denver, CO, March 1994; pp. K.1-K.75. (26) Campbell, J. A. Report No. PNL-10128; Pacific Northwest Laboratory: Richland, WA, 1994. (27) Campbell, J. A. Report No. PNL40127; Pacific Northwest Laboratory: Richland, WA, 1994. (28) Goheen, S. C; McCulloch, M.; Thomas, B. L; Riley, R G.; Sklarew, D. S.; Mong, G. M.; Fadeff, S. K. Report No. DOE/EM0089T, Revision 2; Pacific Northwest Laboratory: Richland, WA, 1994.

since 1957. As a staffscientist, he currently is a member of an organic analysis group and is involved in methods development and implementation for SFE sample preparation and ESIMS with LC or direct sample introduction.

Thomas E. Jones received his Ph.D. from Washington State University and is currently a program manager in the Office of Hanford Environment at PNL. His other activities at Hanford have included directing characterization of high-level radioactive tank wastes and supporting hydrogeological characterization of aquifers beneath the Hanford site.

Monty R. Smith received his Ph.D. in chemistry from Oregon State University in 1982 and is currently a senior research scientist at PNL. His present studies include analyt- Denis M. Strachan received his Ph.D. in ical instrumentation development in the physical chemistry from Iowa State Univerareas of laser ablation ICPMS and autosity. In 1974, after teaching chemistry at Gonzaga University (Spokane, WA), he mated radiochemical separations by IC/ joined Atlantic Richfield Hanford Co. and James A. Campbell received his Ph.D. in ICPMS with beta detection. in 1979 joined PNL. He has developed analytical chemistry from Montana State waste glass and ceramic waste storage University in 1983 and worked for Dow David W. Koppenaal received his Ph.D. Chemical Co. before joining Pacific North- from the University ofMissouri in 1978. He forms and has worked to understand their dissolution in aqueous media. west Laboratory (PNL) (P.O. Box 999, is currently manager of the Atomic and MS P8-08, Richland, WA 99352) in 1986. Molecular Chemistry section at PNL. His reHis research focuses primarily on the devel- search interests lie in the area of atomic Harry Babad has worked for more than 20 opment of techniques using GC/MS, LC, and MS methods, especially ICPMS and TIMS. years in the areas of systems engineering LC/MS to analyze organics in mixed hazand multidisciplinary technical apardous wastes and other difficult matrices. R. M. Bean is a staff scientist and has proaches for nuclear waste management been at PNL for almost 21 years. He reand disposal. He currently serves as an adviR. W. Stromatt received his Ph.D. in chem- ceived his Ph.D. from the University of Utah sory chemist at Westinghouse Hanford Co. and is currently the program manager for istry from Kansas State University in for the waste tank safety and waste tank 1958 and has worked at the Hanford project the Organic Tanks Safety Program. characterization programs.

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ACS III PUBLICATIONS Essential Resources for the Chemical Sciences

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